Subject: Re: More Stateless Catalog use cases
Resent-Date: Thu, 31 May 2001 09:01:42 -0500 (EST)
Resent-From: servicemodel@opengis.org
Date: Thu, 31 May 2001 10:10:04 -0400
From: Doug Nebert <ddnebert@fgdc.gov>
Organization: Federal Geographic Data Committee
To: Rob Atkinson <rob@socialchange.net.au>
CC: Jeff de La Beaujardiere <delabeau@iniki.gsfc.nasa.gov>,
     Service Model <servicemodel@opengis.org>, catalog.wg@opengis.org

>
> Jeff de La Beaujardiere wrote:
>
> > I took an action at today's Catalog/Service Model meeting to
> > write down my Use Case describing a WMS search and what I
> > think Rob Atkinson's is [Rob--correct me if I'm wrong].
> >
> > -Jeff DLB
> >

I don't feel the issues of Full versus Brief are material. My
main concern is where to store and retrieve adequate metadata
for data and services in integrated ways. The current layer-
centered metadata approach is not scalable.

Two Stateless or Stateful Catalog Use Cases: Search for Map Invocation

Option 1:

o User types in search terms against a gateway or catalog of data
  specifying the information content, characteristics, limitations,
  suitable scale range, and service type (class) s/he
  is interested in.

o Data metadata is returned with ISO 19115 qualified Online_Resource
  leads that point to a service 'handle' stored in an instance
  registry.

o The handle is used to fetch the valid parameters for the invocation
  of the map service instance, coupled with the layer name stored
  in the data metadata as a qualifier.

o The client assembles a valid map service request on the
  specific data.

Option 2:

o User types in search terms against a gateway or catalog of data
  specifying the information content, characteristics, limitations,
  suitable scale range, and service type (class) s/he
  is interested in.

o Data metadata is returned with ISO 19115 qualified Online_Resource
  leads that points to the capabilities request URL for the specified
  service.

o The capabilities are fetched directly from the map service
  provider for the invocation of the map service instance, coupled
  with the layer name stored in the data metadata as a qualifier
  such that a service instance registry is not required in this
  case (Data-independent - loosley coupled - services not covered
  in this scenario).

o The client assembles a properly-formed map service request on the
  specific data.

--
Douglas D. Nebert
Geospatial Data Clearinghouse Coordinator
FGDC/GSDI Secretariat   Phone: +1 703 648 4151  Fax: +1 703 648-5755
Pager Messaging:        http://clearinghouse3.fgdc.gov/dougmsg.html